Re: [PATCH RFC v3 4/4] drm/virtio: add VIRTGPU_PARAM_HOST_SHM_PAGE_SIZE to params

[Dmitry Osipenko <dmitry.osipenko@collabora.com>]

On 2/20/25 17:28, Sergio Lopez wrote:
> Add VIRTGPU_PARAM_HOST_SHM_PAGE_SIZE as a param that can be read with
> VIRTGPU_GETPARAM by userspace applications running in the guest to
> obtain the host's page size and find out the right alignment to be used
> in shared memory allocations.
> 
> Signed-off-by: Sergio Lopez <slp@redhat.com>
> ---
>  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 5 +++++
>  include/uapi/drm/virtgpu_drm.h         | 1 +
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> index c33c057365f85a2ace536f91655c903036827312..f112b862c2de4d021fb6a54a080f42ad75034227 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> @@ -117,6 +117,11 @@ static int virtio_gpu_getparam_ioctl(struct drm_device *dev, void *data,
>  	case VIRTGPU_PARAM_EXPLICIT_DEBUG_NAME:
>  		value = vgdev->has_context_init ? 1 : 0;
>  		break;
> +	case VIRTGPU_PARAM_HOST_SHM_PAGE_SIZE:
> +		if (!vgdev->has_host_visible)
> +			return -ENOENT;
> +		value = vgdev->host_visible_region.page_size;
> +		break;
>  	default:
>  		return -EINVAL;
>  	}
> diff --git a/include/uapi/drm/virtgpu_drm.h b/include/uapi/drm/virtgpu_drm.h
> index c2ce71987e9bb816d13a300679336cb756f1cbcf..72db6b3339e0dcaf550acbf5ac4381a6e5c2216d 100644
> --- a/include/uapi/drm/virtgpu_drm.h
> +++ b/include/uapi/drm/virtgpu_drm.h
> @@ -98,6 +98,7 @@ struct drm_virtgpu_execbuffer {
>  #define VIRTGPU_PARAM_CONTEXT_INIT 6 /* DRM_VIRTGPU_CONTEXT_INIT */
>  #define VIRTGPU_PARAM_SUPPORTED_CAPSET_IDs 7 /* Bitmask of supported capability set ids */
>  #define VIRTGPU_PARAM_EXPLICIT_DEBUG_NAME 8 /* Ability to set debug name from userspace */
> +#define VIRTGPU_PARAM_HOST_SHM_PAGE_SIZE 9 /* Host SHM page size, with format PAGE_SIZE >> 12 */
>  
>  struct drm_virtgpu_getparam {
>  	__u64 param;
> 

Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>

-- 
Best regards,
Dmitry